Servo system industry development
1 Introduction
1.1 Overview
Servo motor (servo motor) refers to the engine that controls the operation of mechanical components in the servo system, and is an auxiliary motor indirect transmission device.
The concept decomposition of "AC permanent magnet synchronous servo motor":
- AC: The stator of the servo motor is passed through a three-phase sinusoidal AC (PWM modulation), which is used for excitation and generates a rotating magnetic field.
- Permanent magnet: The surface of the rotor of the servo motor is covered with permanent magnets.
- Synchronization: During operation, the rotational speed of the rotor is the same as that of the rotating magnetic field generated in the stator, that is, it remains synchronous. This is different from the induction motor. The operating condition of the induction motor is that there is a difference (slip rate) between the rotational speed of the rotor and the stator magnetic field, and the rotor relies on this slip to cut the magnetic force lines to generate torque.
- Servo: There is an encoder behind the motor, and its feedback signal forms a closed-loop control with the driver, so it is called a servo.
The servo system is a necessary way to achieve precise positioning and precise movement in the automation industry. The servo system can make the output parameters such as the position, speed and torque of the system terminal actuator accurately follow the change of the input quantity. It consists of a controller at the control level, a servo drive at the drive level, a servo motor at the execution level, and an encoder.
1.2 General application
1.3 Classification
Classified by system power
Large servo refers to the system power greater than 5KW, mainly used to drive heavy machinery and equipment.
The medium-sized servo refers to the power between 1KW and 5KW, which is widely used in the OEM market.
Small servo refers to the system power less than 1KW, mainly in the low-end OEM market.
Classified by power source
1.4 Servo system in industrial control
1.5 Comparison of digital signal drive and analog signal drive
Compared with analog control, the difference between digital control and analog control is that the signal is discrete rather than continuous, it is not easily disturbed during transmission and amplification, and its precision is significantly higher, and advanced control algorithms can be applied through CPU processing and other methods (such as the most Optimal control, artificial intelligence, fuzzy control, neural network, etc.), which improves the reliability and controllability of the servo system.
1.6 Development History
Before the 1950s, the hydraulic servo system was mainly used;
with the development of electrical control technology, the DC servo system appeared in the 1950s and began to be gradually popularized and applied on mechanical equipment;
with the German Rexroth company officially launched the MAC permanent magnet AC servo motor and drive in 1978 Control system, AC servo system began to appear.
In the 1980s, the AC servo system began to be popularized on a large scale; in the
1990s, with the upgrading of electronic control technology, the control technology of the servo system was gradually upgraded from analog signal control to digital signal control technology, thereby improving the response speed of the servo system and control accuracy.
With the development of electrification and digitization, domestic servos have also undergone a transformation process from hydraulic, pneumatic to electrical. At present, the most widely used is the electrical servo system. Among them, AC synchronous servo has become the mainstream product of high-precision servo system.
2 Servo system manufacturers
Industrial robotic arm
Mobile AMR
- Hollysys
- Kinko
- elmo
- …
3 Key indicators and difficulties
4 Three-phase AC inverter (DC to AC conversion)
The servo system used in AGV is actually called a digital AC servo system. AC refers to three-phase alternating current.
Most commercial, industrial, and residential loads require AC power, but AC power cannot be stored in batteries, which is important for backup power.
The polarity of DC power does not change over time like AC power, so DC power can be stored in batteries and supercapacitors . So we can first convert the alternating current to direct current, which can then be stored in the battery, so that whenever alternating current is needed to run the alternating current appliance, the direct current is converted back to alternating current to run the alternating current appliance.
working principle
A three-phase inverter usually consists of five parts: input filter, rectifier, intermediate DC link, inverter and output filter . By integrating these five parts, the three-phase inverter can convert the electric energy of the DC power supply into the electric energy of the AC power supply, and generate a high-quality output voltage waveform. During operation, the main capacitor of the three-phase inverter stores electric energy, the three-phase bridge full-wave rectifier circuit rectifies the power supply, the three-phase half-bridge inverter module generates an output high-frequency AC voltage, and finally the high-frequency AC voltage is converted by the output filter The frequency components are filtered out to obtain a pure output voltage signal .
reference
1. China Business Industry Research Institute – 2018 China Servo System Industry Prospect Research Report
2. Servo System: Import Substitution + Emerging Industries Drive Strong Demand
3. China Servo Market 2019 Research Report
4. Servo System: Intelligent Manufacturing Drives the Great Development of the Industry, Domestic
5. Some industry reports – From iResearch
6. The benefits of three-phase AC inverters
7. Understand the 17 main types of inverters in one article
8. Three-phase inverters
9. Three- phase Inverter working principle
10. Three-phase voltage inverter circuit
11. 【Industry Depth-Industrial Control System 05】Focus on Servo System
12. 【LeiSai Intelligence | Headlines】Motion Control Studio: It’s time to popularize AC servo motors!